This invention relates to tubular remote controls in which one or more push-pull blades are slidable lengthwise in a tubular sheath on spaced ball bearings disposed on opposite sides of each blade. More particularly, the invention relates to a novel ball-cage strip for keeping the ball bearings properly spaced.
Illustrative of such a remote control is that disclosed in U.S. Pat. No. 2,841,029 to Richoux in which the balls are spaced from one another by metal cage strips having openings to hold the individual balls. As shown by Richoux, each opening in the cage strip is provided with transverse walls having a height at least equal to the rolling radius of the ball so that the ball is free to rotate within the opening without risk of the ball escaping the opening. The special structure of the metal cage strip is clearly illustrated by FIGS. 4,5 and 6 of the Richoux patent. It is evident in FIG. 4 of the Richoux patent that rubbing contact exists between the metal ball-cage strip and the metal push-pull flat core. Over prolonged use of the remote control, such metal-to-metal rubbing leads to abrasion and gouging of the metal elements and possible ultimate jamming of the control.
To avoid metal-to-metal rubbing, U.S. Pat. No. 3,667,313 to Young shows a ball-cage strip made of flexible plastic. While plastic ball-cage strips are successfully used in many controls, they cannot be used where the remote control is exposed to high temperatures, say above 400.degree. F.
Accordingly, the object of this invention is to provide an improved ball-cage strip for tubular remote controls that overcomes the undesirable features of the metal and plastic ball-cage strips used heretofore.